(a) Technical Field
The present disclosure relates to an apparatus for controlling a vehicle, and a control method thereof, and more particularly, to apparatus and method for controlling a vehicle with improved motor control performance by easily determining whether to automatically correct an offset value upon determination of a resolver offset while the vehicle is running.
(b) Description of the Related Art
In general, a motor control unit (MCU) is used to control a motor provided in an electric vehicle or a hybrid vehicle. To this end, a resolver is used to measure the absolute position of the rotor with respect to the stator of the vehicle motor.
A resolver is a type of transformer, in which when an excitation voltage is applied to a primary winding to rotate the axis of the resolver, a magnetic coupling coefficient is changed to generate a voltage that changes an amplitude of a carrier in a secondary winding. In this case, windings are arranged such that the generated voltage is changed in the form of sinusoidal waves of sine and cosine with respect to a rotation angle of the axis. Thus, a rotation angle of the resolver may be calculated by reading a carrier amplitude ratio between a sine output and a cosine output.
The resolver operating based on the foregoing principle detects speed information and phase of the motor and provides position information regarding the rotor to an MCU, where position information regarding the rotor is used as information for generating torque and speed commands.
However, measuring an absolute position of the rotor with respect to the stator by using the resolver generates an offset due to various factors such as assembly tolerance between the resolver and the motor, inaccuracy in the position of a coil within the resolver, and the like,
The generated offset makes it impossible to measure an accurate absolute position of the rotor with respect to the stator. Thus, the motor cannot be controlled normally.
Conventionally, in order to correct offset generated in the resolver, waveforms of a line-to-line back electromotive force of the motor and the resolver are analyzed using a measurement instrument such as an oscilloscope, and the offset value with respect to the sensing error is thereby corrected.
However, such a method is performed through manual operation by an operator, requiring much time to correct the offset. Thereby, workload of the operator is increased, and an offset value of every vehicle is required to be corrected, which is impractical. In addition, different offset correction values may be obtained according to differing skills of operators.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.